Al~tract. YBa2SnO~5 has been synthesized and sintered as single phase material for its use as substrate for both YBCO and BiSCCO superconductors. YBa2SnOs~ has a complex cubic perovskite (A2BB'O6) structure with the lattice constant a = 8.430 A. The dielectric constant and loss factor of YBa2SnOs. 5 are in a range suitable for its use as substrate for microwave applications. YBa2SnOs. 5 is found to be chemically compatible wRh both YBCO and BiSCCO superconductors. The thick film of YBCO screen printed on polycrystalline YBa2SnO5. 5 substrale, gave a To(0) of 92K and a critical current density (Jc) of 4x 104 A/cm 2 at 77K. A screen printed BiSCCO thick film on YBa2SnO5. 5 substrate gave Tc(o)= I10K and current density 3 × 103 A/cm 2 at 77 K.